title: Magnetic polarons and large negative magnetoresistance in GaAs nanowires implanted with Mn ions.
abstract: We report on low-temperature magnetotransport and SQUID measurements on heavily doped Mn-implanted GaAs nanowires. SQUID data recorded at low magnetic fields exhibit clear signs of the onset of a spin-glass phase with a transition temperature of about 16 K. Magnetotransport experiments reveal a corresponding peak in resistance at 16 K and a large negative magnetoresistance, reaching 40% at 1.6 K and 8 T. The negative magnetoresistance decreases at elevated temperatures and vanishes at about 100 K. We interpret our transport data in terms of spin-dependent hopping in a complex magnetic nanowire landscape of magnetic polarons, separated by intermediate regions of Mn impurity spins, forming a paramagnetic/spin-glass phase.
authors.affiliation: Solid State Physics/The Nanometer Structure Consortium, Lund University , Box 118, SE-221 00 Lund, Sweden.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Kumar
authors.forename: Waldomiro
authors.initials: W
authors.lastname: Paschoal
authors.forename: Andreas
authors.initials: A
authors.lastname: Johannes
authors.forename: Daniel
authors.initials: D
authors.lastname: Jacobsson
authors.forename: Christian
authors.initials: C
authors.lastname: Borschel
authors.forename: Anna
authors.initials: A
authors.lastname: Pertsova
authors.forename: Chih-Han
authors.initials: CH
authors.lastname: Wang
authors.forename: Maw-Kuen
authors.initials: MK
authors.lastname: Wu
authors.forename: Carlo M
authors.initials: CM
authors.lastname: Canali
authors.forename: Carsten
authors.initials: C
authors.lastname: Ronning
authors.forename: Lars
authors.initials: L
authors.lastname: Samuelson
authors.forename: Håkan
authors.initials: H
authors.lastname: Pettersson